Spy-watchers are sounding the alarm about a growing temptation for the nation's intelligence agents to covertly "disrupt" suspected terrorists while sidestepping open processes in Canadian courts.

The Security Intelligence Review Committee (SIRC) urges that Public Safety Minister Vic Toews take a more hands-on role in regulating and monitoring such spy operations, to ensure that the government has "full knowledge" of what the Canadian Security Intelligence Service (CSIS) gets up to.

"Disrupting" suspected terrorists is a legal grey area that can involve everything from aggressive interviews by state agents, to overt surveillance of terrorism suspects, to techniques of more questionable legality. These processes are, by nature, designed to thwart plots in nascent stages, when federal agents feel there is not sufficient evidence to take to court.

The conclusions of SIRC, a watchdog body created to keep tabs on Canada's spy service, come from its annual report released this week. In 1984, the CSIS-watched-by-SIRC model replaced the more freewheeling RCMP security service, after that agency was discredited for a host of illegal disruption campaigns.

During the 1960s and 1970s, the Mounties were exposed perpetrating dirty tricks in the name of fighting terrorism. Most glaringly, the RCMP burned down a Quebec barn to prevent a planned meeting there between FLQ separatists and Black Panther radicals. Dozens of other lesser disruptions, including unauthorized police break-ins and fake-letter campaigns, were also unveiled.

Now SIRC wants Canada's spies to be more mindful of past excesses, especially as CSIS's appetite for risk and global counterterrorism grows. The spy service's budget has tripled in the past decade. Its agents are targeting everyone from Taliban bomb-makers in Afghanistan to undocumented Tamil migrants setting sail for Canada from Southeast Asia.

The fear is that more aggressive disruption campaigns will certainly follow. "The service's statutory mandate resulted from a series of illegal acts and practices carried out by the RCMP," cautions the SIRC report. Any disruption campaigns go "to the heart of ministerial accountability for the service and therefore should be conducted with the ministers' full knowledge," the report says.

There is no allegation that CSIS has done anything illegal, and CSIS insiders counter that Mr. Toews is by law kept in the loop on CSIS's most invasive spying techniques.

"There isn't a triggering event," Susan Pollack, executive director for SIRC, said in a conversation on Tuesday, adding that the concerns the watchdog agency is expressing are, at this point, mostly hypothetical.

But SIRC says there is clear pressure on CSIS to step up disruptions, given the inherently shadowy battle against global terrorism on one hand and CSIS's long-standing aversion to transparency on the other.

"CSIS does not discuss any specific operational issues or methodologies," Isabelle Scott, a spokeswoman, said in an e-mailed response to Globe questions about disruption.

When pressed, however, she did say that spies "may consider asking a family member or community leader" close to a terrorist suspect to assist in dissuading extremism. Such interventions and other, unspecified techniques "may be sufficient in foiling planned acts which threaten the safety and the security of Canadians," she said.

RCMP detectives, and not CSIS operatives, may be the state agents better situated to disrupt terrorists, according to SIRC. In fact, the Mounties claimed in a recent report to have disrupted 14 terrorist groups in 2007 - but provided no details as to who, when or how.

Paul Kennedy, formerly a top security bureaucrat, said there is nothing inherently wrong with disruption. "I don't think the word by itself is bad," he said, pointing out that it is a time-honoured technique used by state agents when all else is likely to fail. Counterterrorism court cases are notoriously hard to prosecute.

Still, Mr. Kennedy, who has been given the task of watching both the RCMP and CSIS in his career, says there is a clear public interest in reining in any excesses by state agents. "If you don't circumscribe disruptive activities," he said, "one may cross the line and we may find ourselves back where we were."

Some past examples of 'overt surveillance' and disruption by Canadian spies

Known examples of "disruption" campaigns by Canadian agents are rare, but some acknowledged and apparent ones do exist.

1972: The RCMP Security Service burns down a barn in rural Quebec to prevent a meeting between suspected FLQ separatists and Black Panthers.

This is the most glaring of hundreds of other questionable - arguably illegal - police anti-subversion activities of that era. They lead to a judicial inquiry to urge the creation of a more constrained civilian spy service.

1984: The Canadian Security Intelligence Service is created as a domestic agency. Over time it grows less passive and domestic, and more aggressively operational and outward-looking.

2001: RCMP and CSIS state that agents engage in "overt surveillance" of certain Canadian Arabs suspected of links to al-Qaeda - yet who have committed no crimes. Teams of cars follow certain individuals.

Closed-circuit cameras are conspicuously installed outside residences. The surveillance prompts individuals to leave the country - some of whom are subsequently arrested and tortured overseas.

2005: CSIS agents meet the parents of young radicals in Toronto to tell them their children risk becoming terrorists. One teenager takes offence and hatches a plot to bomb Toronto's CSIS headquarters. Zakaria Amara is now serving a life sentence.

2008: An RCMP fiscal report claims that the Mountie counterterrorism detectives "disrupted 14 groups and/or individuals" in that year, but gives no details.

2009: CSIS agents approach security staff at the Ottawa Hospital, asking them to keep an eye on an X-ray technician there. Mounties later charge Misbahuddin Ahmed in connection with the RCMP's "Project Samossa" operation.

2010: CSIS director Richard Fadden tells Parliament his spies "have saved Canadian lives" in Afghanistan without specifying how. CSIS is believed to have a clandestine role in disabling Taliban bomb-making cells.

2010: A Toronto judge faults CSIS "threats and intimidation" for leading a Muslim preacher to hand over incriminating evidence to authorities. Judge Jane Kelly tosses out the case.